Manufacture of bleaching-powder.



l. W. MOORE.

MANUFACTUEE 0F BLEACHING POWDER.

APPLNIAIIH FILED FEB. 5. |918.

Patented .my 16,

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JOSEPH WILLIAM'. MGORE, OF RUNCORN, ENGLAND, ASSIGNOE, T0CTN'EEfKELLEEE,

ALKALI COMPANY, LIMITED, OF LOEDON, ENGTAND.

Mai'rurricrunn or spaarzame-servons.

Speciication of Letters Patent.

Application filed February 5, 1918. Serial No.. 215,528.

e To all whom it may concern:

- Be it known that I, JOSEPH WILLIAM MOORE, a subject of the King ofGreat Britain, residing in Ituncorn, England,have

invented certain new and useful Improvements in the Manufacture ofBleaching- Powder, of which the following is a speciication.`

In the .manufacture of bleaching powder, by causing lime and chlorin topass through a rotating tube, or series'of connected rotating tubes, itis of very considerable commercial and technical importance to obtainthe gas issuing 'from the tube, free or almost free, from unabsorbedchlorin, while the bleach is being continuously produced.

Over forty years 'ago (see Hendersons British specication'No. 3080 of1871) it was proposed to charge linie with chlorin by passing chlorin upinclined tubes or -cylin-f ders .about 40 feet long, through which limewas made toY travel by imparting rotation to the tubes or cylinders, orto screws inside them. The latter principle is embodied in the now wellknown apparatus, patented by Hasenclever in 1888, British specificationNo. 17012, but the rotating tube method, has so far as we know,hitherto, never been successfully attempted on the commercial scale.

Lunge in Sulphurc Acid and Alkali, vol.

I111, page 468 (1896 edition) says:

All mechanical bleaching' powder chainbers (other than Hasenclevers)hitherto erected have been abandoned after a short period of work,either because the machinery failed, or because the bleach came out Weakor both.

Among the drawbacks to the before-inentioned proposals are that theshafts and cylinders rapidly corrode and the corrosion products mix withthe powder decomposing same to some extent, impairing its keepingqualities and injuring its color, and where Scrapers or feeders areemployed the powder is compressed against the cylinder wall forming anextremely hard and trouble-- to be vperiodically` some crust which haschipped oil' involving much disagreeable and expensive work. In additionto these drawbacks the gas issuing from such a rotating tube asdescribed by Henderson contains a very considerable proportion ofunabsorbed chlorin if a full output of strong bleach is maximum outputof high strengthbeing produced and finally the working costs I -arenecessarily high.

-According to `my inventionY bleaching powder may be made of high'strength inV an inclined rotating cylinder which in respect of lengthmay be compared with the tube mills used in cement works. The best len happears to be about 80 feet, which is dou le that suggested inHendersons aforesaid specification. The necessity for this great lengthis chiefly owing to theneed for thorough stirring of the partiallychlorinated lime as it .descends the c linder and more particularly isit needed t at the stirring should be prolonged while the material is inthe presence of the most concentrated chlorin, namely in the lower halfof the length of the cylinder. Mere lengthening of the cylinder ascoinparedwith Hendersons suggestion does not, however, insure asatisfactory product or fulfil the requirement that the chlorin must besubstantially completely absorbed. It being necessary to work on the.counter-current principlev the chlorin must hel admitted at the bottomof theY cylinder and there is considerable difficulty in causing thechlorin to travel up the cylinder unless it is under such pressure thatleakage from the cylinder cannot be avoided. `This diiiiculty isovercome in my invention by connecting an outlet at the top of thecylinder with a suction v power so as to maintain a slight suction inthe cylinder.

lVithout minimum length I may say that for satisfactory results arotatingl tube not much shorter than 80 feet must be used. A suitableinside diameter is 20 inches. Such a tube or cylinder is illustrated inthe accompanying drawings, in which Figure 1 is a longitudinal sectie-nand Fig. 2 an end elevation.

The cylinder a, bolted together, as at made in cast iron sections b, ismounted in wellknown manner on roller bearings c at an ap-` propriateinclination, say 1 in 24. It is caused to rotate by worm gearing d atthe rate of, say, thirty revolutions per hour. The cylinder is lined-with glazed earthenware tiles w. It is connected at its ends by meansof glands e with stationary boxes f, g respectively. The box f has anopening h for exhaust of gases and an opening which limiting myself to1an exact ter is rotated by gear m from the cylinder a and conveys thelime from hopper n to pipe z' down which it falls onto an inclined chuteo and then into the cylinder a. The lime in the helical conveyer Z formsa sufficiently gas-tight packing.- A suitable rate of feedl of the limeyin an apparatus of the dimensions here given is about 8 tons per week inwarm weather and 10 tons per week in cold weather. The box g has anupper opening p for admission of gases and the lower opening `connectedwith a pipe g closed at its lowerV end by a slide v which is` openedintermittently to permit the finished bleaching powder to fall into thecask s. Inspection doors t are provided in the cylinder a. The boxes fand g have laterallyv extending brackets u supported .by posts o carriedby brackets w on the uprights which carry theend roller bearings c.

The exhaust opening L in the box f is connected with a suction pump soas to draw the gases away from the apparatus and maintain a slightsuction therein, to assist thev upward travel of the chlorin and preventescape of chlorin.

Having thus described the nature of the said invention and the bestmeans I know of carrying the same into practical effect, I claim Aprocess for the manufacture of bleaching powder, which consists incausing lime to travel down an inclined rotating tube about 8O feetlongand causing chlorin to travel up the tube by applying a slight suctionat the upper part of the tube. l

'In testimony whereof I have 'signed my name to this speciication inthe/presence of two subscribing witnesses7 JOSEPH WILLIAM MOORE.

